The main object of this study was the control of the sesiid borer Synanthedon myopaeformis (Lepidoptera) with entomogenous nematodes of the genera Steinernema and Heterohabditis. Three speciesof entomopathogenic nematodeswere evaluated for suppression the population of the apple clearwing borer (ACB; Synanthedon myopaeformis) attacking apple trees (Pyrus malus) in Fayoum and Giza Governorates throughout 1998 and 1999, respectively utilizing Steinernema carpocapsae, S. glaseri, and Heterorhabditis bacteriophora. In field trials, which were located in Fayoum, utilizing entomopathogenic nematodes and the organophosphorus Basudin “Diazinon" 60% EC, nematodes were applied as bark spray in spring (early April) and autumn (early September) as two application methods (sprays wetting bark and spray dry bark) using a knapsack sprayer. Examination of pupal skins revealedthatnematode reduced ACB population in all treatments, with control ranging from 28.8% to 85.9%. Spring treatments were preferable to application since they significantly gave high control (61.5 – 85.9%, 50.9 – 65.0% and 32.5 – 46.6% for S. carpocapsae, S. glaseri, and H.  bacteriophora, respectively ) as compared to autumn treatments(51.4 – 63.7%, 42.7 – 55.1% and 28.8 – 33.7%, respectively). Also, wetting the tree bark prior to nematode application significantly reduced the number of pupal skins as compared to nematode treatment applied to dry bark. Basudin treatment showed relatively low reduction in ACB pupal skins relative to the control In Giza, trunks of the grafting knots of infested apple trees were treated as trunk sprayer and a nematode-water-suspension of a 'collar' consisting of sponge - rubber material. The ‘collar'application reduced thehost larvae with 95.7, 86.2 and 54.7%forS. carpocapsae, S. glaseri, and H.  bacteriophora, respectively whereas trunks treated with the knapsack-sprayer resulted in mortality rates of 85.6, 65.1 and 37.5%, respectively . In all experiments the mortality rate due to treatment was strongly depended on the humidity conditions. This effect could be excluded at the time of application using wetting the bark and the collar techniques.